1. Field of the Invention
The present invention relates to a claw pole motor stator in which teeth for N phases juxtaposed in an axial direction have coils for N phases wound therearound within a plane perpendicular to an axis.
2. Description of Related Art
A type of claw pole motor stator is disclosed in Japanese Patent Application Laid-open No. 7-227075. The stator is provided with three stator units that correspond to each of a U-phase, a V-phase, and a W-phase. Each stator unit is formed with a U-shaped cross-section having two sets of teeth spaced from each other in the axial direction, and a return path to connect the teeth at radially outer ends thereof. By energizing an annular coil housed within the U-shaped cross-section stator unit, an independent magnetic path is generated, which magnetizes two types of poles having different polarities. The poles are projectingly provided at radially inner ends of the two sets of teeth of the stator unit and face a rotor.
However, in the above-mentioned conventional arrangement, the stator is formed by stacking the U-phase, V-phase, and W-phase stator units in the axial direction. Since each stator unit has an annular slot housing a coil therewithin and is further provided with two teeth sets and two types of poles, the axial thickness of the stator unit is disadvantageously large, and the axial dimensions of the stator are disadvantageously increased.
In particular, when a claw pole motor is disposed between an engine and a transmission of a hybrid vehicle, it is desirable that the thickness of the motor be as thin as possible. Because the above-mentioned conventional claw pole motor uses a relatively thick stator, it is rather difficult for the conventional motor to meet this objective.